A laser is an apparatus which amplifies or oscillates an electromagnetic wave having a very short wavelength using quantum mechanics. The laser is referred to as a quantum oscillator or a molecular oscillator. The term “laser” is originated from Light Amplification by Stimulated Emission of Radiation.
Light emited when an object is burned or light emitted from a fluorescent lamp is generated from individual atoms or molecules heated at high temperature. Such light has a large number of different wavelengths even if the light is generated from the same kind of atoms or molecules. Light generated from individual atoms or molecules is the group of diverse lights having no relations with each other. However, a laser beam is coherent much more than other light beams and goes straight almost without diverging.
Such laser is wide spread in human life. A representative is a laser pointer which is an apparatus pointing at a direction by radiating a laser beam generated by a laser diode at a particulat position of a target object. The laser pointer is made compact so that a user can conveniently carry.
Meanwhile, in the industrial world including industrial sites, construction sites, and interiors and in daily life, a measuring tape is usually used to measure a distance. However, it is difficult for a user along to measure a size of a large object or place or a high object or place with the measuring tape. Moreover, since the measuring tape is easily bent or curved, it may be difficult to accomplish accurate measurement. To overcome this problem, a laser distance measuring apparatus, which counts time until an emitted laser beam returns back from a target object and measures a distance to the target object, has been developed.
Such laser distance measuring apparatus emits a laser beam, receives the laser beam reflected from a target object, and measure a distance to the target object. Accordingly, it is necessary to accurately receive the laser beam. However, when a user measures a distance while holding the laser distance measuring apparatus with the hand, it is difficult to receive a laser beam reflected from a target object if the laser beam is refracted and reflected by the target object.